Progress on Resource Adequacy Assessment for 2017 Steering Committee Meeting August 30, 2012

Outline Assumptions and uncertainties Current assessment Changes from last year’s assessment Tech committee action items The “Message”

Assumptions Existing resources (sited and licensed) 6th plan conservation Markets NW: all in winter, 1000 MW in summer SW on-peak: 1700 MW winter, 0 in summer SW off-peak: 3000 MW year round

Uncertainties Explicitly modeled Not modeled Water supply Temperature load variation Wind Forced outages Not modeled Economic load growth Uncertainty in SW market Variations in maintenance schedules Systemic variations in wind modeling

Reference Case

Most Positive Case CGS in service, good wind set, no false positives

Least Positive Case Bad wind set

Changes from Last Year’s Assessment Last year (for 2015) LOLP = 1% Current (for 2017) LOLP = 7% What happened? Data errors Modeling changes Real life changes

Changes from 2015 to 2017 Loads (mostly data errors) Base load increase 850 MWa (from original 2015 forecast) DSI double counting (300) 850 – 300 = 550 Conservation double counting (170) 550 + 170 = 720 Pumping load double counting (130) 720 – 130 = 590 Net load increase 590 MWa

Changes from 2015 to 2017 Resources New resources 100 MWa (real) New hydro 270 MWa (real) 100 + 270 = 370 Contract adjustments (-530 MWa) 370 – 530 = -160 MWa (mostly error) Net resource increase -160 MWa Net overall change 750 MWa load increase SW on-peak market down 1,300 MW

LOLP Trace back Last year: LOLP = 1% 750 MWa load increase +3.4% LOLP = 1 + 3.4 = 4.4% 1300 MW less SW Market +1% LOLP = 4.4 + 1 = 5.4% Temp-correlated wind +1% LOLP = 5.4 + 1 = 6.4% Revised model +0.5% LOLP = 6.4 + 0.5 = 6.9%

Real Changes from 2015 to 2017 Resources Generating resources up about 100 MW Wind increases 1,300 MW Temperature-correlated wind data Hydro increases by 270 MWa SW on-peak winter market decreases by 1,300 MW

Real Changes from 2015 to 2017 Loads Loads increase by about 300 MWa Average summer peak increases 500 MW Average winter peak increases 300 MW Firm contracts about the same Last year’s assessment was wrong (should have been higher)

Technical Committee Actions Review 2017 load and resource data Explain how conservation is incorporated into the load and at what level Obtain CEC assessment of loads and resources for 2017 to update the SW on-peak and off-peak market availability Review south-to-north intertie capacities Review curtailment records for potential false positives

The Message Single LOLP value can be misleading LOLP is likely to be greater than 5% Does not mean a recurrence of the 2001 crisis Relying only on existing resources and conservation yields a power supply with a likelihood of curtailment above our tolerance level The “gap” can be filled by generating resources, demand response or more conservation. But that is a separate process from an adequacy assessment